特點：·準確的回程損耗/SWR測量·可精確的測試傳輸線和天線·免受現場RF干擾·距離錯誤窗口顯示功能（S120A，S251A/B）·損耗/收益存放（S114B，S332B）·可選瓦特計·可選內置T型連接器（S251A/B）·合成器精確到75ppm技術指標ModelS331AFrequencyrange25to3300MHz(S331A)25to4000MHz(S400A)Freqeuncyaccuracy(CWmode)75ppmFrequencyresolution100kHzImmunitytointerferingRFsignalsupto^*2-15dBmReturnlossSWR Resolution:0.1dB(S120A,S251A)S810A,S818A,S820A)Returnloss:0to54dBSWR:1to65Horizontalrange:0to128*(resolution)Horizontalresolution,rectangularwidowingresolution(meter):Coax:(105*10^8)(up)/△frequency^*3Waveguide:(1.5*10^8)(√(1-(FF1)^2/√frequency)^*4monitor,Option5)Detectorrange:-50to+20dBm,10nWto100mWResolution:0.1dB,0.1*WTracememory40(S331AandS400A)50(S120AandS251A)70(S800Aseries)50(S120AandS251A)70(S800Aseries)^*54(S120AandS251A)6(S800Aseries)RFpowerdetector:+20dBm,50ΩTemperatureStorage:-20℃to75℃Weight1.36kg(3.0lbs.)nom(S120A,S251AandS800Aseries)SizeGeneralRS232:9-pinD-sub,threewireserial